In the field of television broadcasting, broadcasting using a display size having a length-to-breadth ratio of “4:3” (length=4, breadth=3) has been conventionally most frequently used. Presently, however, “16:9” broadcasting called wide broadcasting is also beginning to be popular. General household television monitors are also classified into those having “4:3” display screens and those having “16:9” display screens.
Furthermore, many digital video cameras have a function called a “wide image capturing mode”, i.e., have a function of capturing an image at a wide field angle of “16:9”, in addition to image capturing at a field angle of “4:3”. A general wide image capturing mode mainly has two recording/display forms.
In one form, display, output, and recording are performed by reducing effective image lines in order to form an image having a field angle of “16:9” in a field angle of “4:3”. When this image is displayed on a display device having a field angle of “4:3”, the image having a wide field angle of “16:9” is displayed on the “4:3” screen with black belts being displayed above and below the image, i.e., so-called letter box display (to be referred to as LB display hereinafter) is performed. In this case, the vertical resolution of an effective image is ¾ that of “4:3” full-screen display (in the case of NTSC, 480 lines→360 lines), so the image quality deteriorates.
In the other form, display, output, and recording are performed at a field angle of “4:3” without reducing vertical effective image lines of a “16:9” wide image. When this image is displayed on a display device having a field angle of “4:3”, a vertically long image (an image which is horizontally compressed and vertically extended), i.e., a squeezed image is displayed on the “4:3” screen. In this case, the image quality does not deteriorate because the number of effective lines remains the same as in “4:3” recording. However, if an image like this is directly displayed on a display device having a “4:3” field angle, a vertically long image having an incorrect aspect ratio is displayed. Therefore, a “16:9” image having a correct aspect ratio is generally displayed on a television set having a “16:9” display screen capable of wide display, or on a television set having a “4:3” display screen capable of LB display.
On the other hand, a digital video camera has an EVF (Electrical View Finder) or openable/pivotal liquid crystal display as a display function of the camera body, and has a composite video output or S terminal output as a video output to an external TV monitor. Some digital video cameras capable of image capturing at HD (High Definition: the number of horizontal lines is 1,080i or 720p, i is an abbreviation of interface display, and p is an abbreviation of progressive display) use a “16:9” wide EVF or wide liquid crystal display panel. However, general consumer products are digital video cameras which perform image capturing at SD (Standard Definition: the number of horizontal lines is 480i for NTSC and 576i for PAL, i is an abbreviation of interlace display), and use an EVF or liquid crystal display panel having a field angle of “4:3”.
When a digital video camera thus having only a “4:3” EVF or liquid crystal display panel is set in a “wide image capturing mode”, i.e., in an image capturing mode using a field angle of “16:9”, a wide image can be monitored at a correct aspect ratio by performing LB display having upper and lower black belts on the display screen of the “4:3” EVF or liquid crystal display panel. However, some products put on the market display squeezed images on the display screen of a “4:3” EVF or liquid crystal display panel. On these products, captured images cannot be monitored at a correct aspect ratio.
Also, in a video format environment, products compatible with not only the conventional NTSC or PAL system but also a high-definition image (HDTV system) having a higher resolution are put on the market. Various corresponding digital formats are defined by organizations such as ITU (International Telecommunication Union) and SMPTE (Society of Motion Picture and Television Engineers).
Recently, products capable of recording and playing back both SD images and HD images are commercially available as digital video cameras for consumers. Some products can output, by using the HDTV system, an HD image to be played back to a display device capable of receiving and displaying an HD image, and can also output, in accordance with the SD specification, an image having a resolution down-converted from that of an HD image to that of an SD image to a display device capable of receiving and displaying an SD image (e.g., Japanese Patent Application Laid-Open No. 2002-125193).
On this background, when an image is to be displayed on a digital video camera in a wide image capturing mode, for example, if the vertical resolutions of this image and OSD (On Screen Display) are together converted to perform LB display on, e.g., the “4:3” display screen of an EVF or liquid crystal display panel of the digital video camera, fine characters of text information and the like are sometimes blurred or missing because the number of vertical effective lines decreases to ¾. Especially when a simple thinning process such as a process which removes one line for every four lines is performed in LB display, the quality of OSD significantly deteriorates as shown in FIG. 8B or 8C compared to normal display as shown in FIG. 8A. This makes OSD difficult to recognize. Even when line resolution conversion is performed by filtering using a digital line filter or the like, the visibility of fine characters and the like unavoidably deteriorates.
By contrast, the deterioration of OSD can be avoided if only an image is displayed by the LB size. In this case, however, the position of OSD deviates from an intended position in the image. Therefore, if the position of OSD with respect to the image has a meaning, e.g., if an AF frame indicating the in-focus position of auto-focusing or a selection frame surrounding a thumbnail image is to be displayed, the positional shift between the image and OSD poses a problem.
If there is only one display destination or output destination, it is relatively easy to adjust the OSD position in accordance with each individual mode. However, if output modes are different, e.g., if a squeezed image is to be output to one display/output destination while an LB image is to be output to the other, it is difficult to control the operation by using common OSD information.